glamor: Only use dual blending with GLSL >= 1.30
It can't be used with older GLSL. Fixes a crash when attempting to anyway.
Closes: #97 (closed) Fixes: e7308b6c "glamor: Add support for CA rendering in a single pass."
/cc @airlied
It can't be used with older GLSL. Fixes a crash when attempting to anyway.
Closes: #97 (closed) Fixes: e7308b6c "glamor: Add support for CA rendering in a single pass."
/cc @airlied